The present invention relates in general to concrete building panels, and, more particularly, to means for attaching concrete building panels to buildings.
Precast concrete wall panels are being widely used in the building industry and can be custom made, which may prove to be very expensive and inefficient, or can be formed in an automated process. A panel formed by an automated process is disclosed in U.S. patent application Ser. No. 811,300, filed Jan. 29, 1977.
As use of precast concrete wall panels increases, the method and means for attaching those panels to building structures becomes more important. Such attaching means should attach the wall panel to a building in an efficient manner, yet in a manner which is secure enough to safely withstand all of the stresses to which a building is subject. Therefore, in addition to the usual criteria, the following criteria should be met by the means used to attach precast concrete wall panels to buildings in modern buildings: (1) during the manufacturing process, the attaching means should be attachable to a form by the use of double faced tape, or the like, but in any event, in a manner which does not require that holes be drilled in steel forms; and (2) the attaching means should have a shear capacity sufficient to transfer roof diaphragm shear to the wall panels.
A further important consideration in modern building construction involves movement of building elements relative to each other. Such relative movement may occur due to normal building settling in any geographic area, but is an especially important factor in areas having the possibility of earthquakes, or so-called seismic zones.
Such relative movement can be accounted for in the wall panel assemblies simply by making the wall panel attachment means strong enough to overcome the forces developed under such conditions. However, such a method can be very expensive and still not adequately account for the relative movement.
Furthermore, the means used to attach wall panels to buildings should have a capacity to account for production, erection and job site tolerances.
There are many different devices known for attaching concrete wall panels to buildings. For example, one device includes a weld plate cast into the concrete panel which is then welded rigidly to the building structure at the time of erection. While this type of device is suitable for custom-type panels which permit accurate placement of weld plates in predetermined positions, such a device is not suitable for concrete panels made on a production automated long line system, nor are production, erection or job site tolerances adequately accommodated by such a device.
The inventor is also aware of hanger devices suitable for concrete work. Examples of such hanger devices are disclosed in U.S. Pat. Nos. 1,201,540, 1,924,884, 1,933,536 and 1,491,571. However, none of these devices are suitable for supporting a concrete building panel on a building in a manner which satisfies all of the above-stated requirements, nor are any of these devices even suitable for supporting a concrete wall panel, such as those used in modern buildings, on a building. Other devices used in building construction are disclosed in U.S. Pat. Nos. 1,548,214 and 2,133,134.
Thus, the known devices are not disclosed, nor suitable for use in attaching a precast concrete wall panel formed in an automated long line process to a building in a manner which accommodates movement of building elements relative to each other, and especially such relative movement induced in seismic zones. Such seismic zone relative movement may be quite severe, and thus should be accounted for, but heretofore has been essentially overlooked.